O.S. SPEED R2104 is a factory tuned engine solely developed for 1/8 racing competition. The new engine boasts 9-port piston liner to improve torque in low-middle power range. It produces enough power as designed even in high traction tracks. The redesigned crankshaft counter weight enables smooth power transition from low to top. Distance of each fin of the heat sink head is enhanced for better air flow for cooling and better balance. The heat sink head is anodized in two colors; black and red.